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Hemodynamic performance of the 21-mm St. Jude BioImplant prosthesis using dobutamine Doppler echocardiography
1Bristol Heart Institute, Department of Clinical Radiology, University of Bristol, United Kingdom.
Insights
Small St. Jude BioImplant aortic prostheses (21-mm) show suboptimal hemodynamic performance. Gradients suggest mild to moderate aortic stenosis, even under stress conditions.
Area of Science:
- Cardiovascular Surgery
- Medical Devices
- Echocardiography
Background:
- Aortic valve replacement is a common procedure.
- Small-profile prosthetic valves are increasingly used.
- Assessing hemodynamic performance under stress is crucial.
Purpose of the Study:
- To evaluate the hemodynamic performance of small size (21-mm) St. Jude BioImplant aortic prostheses.
- To assess valve function at rest and during dobutamine-induced stress.
Main Methods:
- Dobutamine echocardiography in 11 patients with 21-mm St. Jude BioImplant prostheses.
- Measurements included effective orifice area, mean gradient, and performance index.
- Cardiac output determined by Doppler in the left ventricular outflow tract.
Main Results:
- Dobutamine increased cardiac output by 56% (p <0.0001).
- Mean transvalvular gradient increased from 30.1 mmHg at rest to 49.3 mmHg at max stress (p <0.0005).
- Performance index increased from 0.29 to 0.40 (p <0.0005).
Conclusions:
- The 21-mm St. Jude BioImplant prosthesis demonstrates suboptimal hemodynamic performance.
- Transvalvular gradients indicate mild to moderate aortic stenosis at rest and stress.
- Body surface area did not influence hemodynamic changes under stress.
Abstract:
This study examines the hemodynamic performance of small size St. Jude BioImplant aortic prostheses using dobutamine echocardiography. Eleven patients (3 women, mean age 75 years) who had undergone aortic valve replacement with a size 21-mm St. Jude BioImplant aortic prostheses at 10.8 +/- 5.1 months (SD) previously were studied. Dobutamine infusion was started at a rate of 5 microg/kg/min and increased to 10 microg/kg/min, and subsequently to 20 microg/kg/min at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, mean gradient, and the performance index across each prosthesis were calculated and cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract. Stress dobutamine increased heart rate and cardiac output by 51% and 56%, respectively (both p <0.0001), and the mean transvalvular gradient increased from 30.1 +/- 7.5 mm Hg at rest to 49.3 +/- 11.5 mm Hg at maximum stress (p <0.0005). The performance index increased progressively from 0.29 +/- 0.05 at rest to 0.40 +/- 0.10 at maximum stress (p <0.0005). Regression modeling analyses demonstrated that the maximum stress gradient was independent of all variables except the resting gradient (p = 0.03). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress. Thus, these data demonstrate that the size 21-mm St. Jude BioImplant prosthesis exhibits suboptimal hemodynamic performance with transvalvular gradients consistent with mild to moderate aortic stenosis, both at rest and under stress conditions.